Japanese patent JP2000241276 describes a known sensor to measure the pressure of a fluid. The known sensor comprises a diaphragm being flexed upon receiving a pressure to be measured, a first magnet secured to the diaphragm, a second magnet of same polarity secured oppositely to the first magnet, and a Hall element comprising a Hall IC disposed between first and second magnets.
The outer circumferential part of the diaphragm is fitted fixedly in a case of the pressure sensor. To fix the diaphragm a metal is used, for example, stainless steel which has a big intensity and rigidity. This is because an oil pressure that may occur in the sensor is about 10 kgf/cm2 (kilogram-force per square centimeter).
Throughout the Figures, similar or corresponding features are indicated by same reference numerals.
List of Reference Numerals:100a force sensor102a first surface104a second surface106a resilient means108a flexible coupling110a distance sensor122a force124a force130an object200a force sensor202a supporting side204a base side206a space208a resilient body300a force sensor302a closed space400a graph of a measured signal402a respiration cycle404a disturbance500a force sensor502an cross-section line504a flexible cover506a reference line604protection glass606sensor holder608a resilient means holder702a flexible base cover800a pressure sensing system802a body supporting means804a supporting side806a base side808a supporting surface810a space900a heart rate and respiration sensor902a wearing means904an elastic connection906an attachment base1100a mattress1102a force sensor